Impact energy temperature dependence

Ref 22, pp 161-62. Under the title "Thermal Effect of Impact is discussed initiation of liquid expls, such as NG, NGc, etc. It differs from initiation of solid expls (discussed on p 153 of Ref 22) in that there is no friction between crystals as in solids, but everything depends on rise of temperature created by adiabatic compression of gas or vapor in minute bubbles.. For example, with NG contg a bubble as small as 0.1 mm in diam 100% explns can be obtd with impact energy of 400 gram-cm, while 10 to 10 g-cm are required when no gas bubble is present. The temp T2 reached in a bubble due to adiabaric compression of the gas depends, in the case of ideal gas, on the... 

Figure 4. Temperature dependence of impact energy for Vs inch thick notched Izod specimens cut from compression molded sheets of BPA polycarbonate and two of its block polymers. A 15% silicone, B 25% silicone. Silicone DPn = 20.

The temperature dependence of the absorbed energy for standard specimens is shown in Figure 1. Impact behaviors and fracture modes of edge notched specimens depending on temperature were reported elsewhere (9, 10). In edge notched specimens of unidirectional roving reinforced material (GC 68 wt % ), cloth laminates, and mat reinforced material the fracture mode changed with temperature all materials re-... 

Fig. 13.37 (a) The dependence of the Izod impact energy on temperature for a rubber-modified HDPE sample, derived from the far end of an injection-molded bar. 

Fig. 13.41 The temperature dependence of the critical fracture energy Gic in DGEBA epoxy-resin thermosets, modified either by rubber particles or by debonding glass spheres, either in tests of conventional extension rates or in Izod impact tests, compared with the generally flat behavior of unmodified epoxy resin (Kinloch (1985) courtesy of Springer).

Fig, 11,16 The dependence of notched Izod impact energy on temperature for the HDPE/CaC03 (80 20vol./vol.) and HDPE/ethylene-octene rubber (78 22 vol./voL) blends (From Bartczak et al. (1999c) reproduced with permission of Elsevier)... 

The temperature dependence, though small, can have a significant impact on carrier densities. A heuristic model of the temperature dependence of Eg is Eg T) = EglOK) — aT /(T + fi). Values for the parameters in this equation are provided in Table 2.5. Between 0 and 1000 K, the values predicted by this equation for the energy gap of GaAs are accurate to about 2 x 10 eV. 

Electrode reaction rates. Typically, electrode reactions follow Arrhenius behavior. As a consequence, these losses decline exponentially with increasing temperature, usually more than off-setting the reduction in ideal potential. The higher the activation energy (and hence usually the losses) the greater the impact of temperature. The impact of total pressure depends on the pressure dependence of rate-limiting reaction steps. 

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